From f84ecd5b6385dca1398b112a27cd56b9081c35eb Mon Sep 17 00:00:00 2001
From: Per Hultqvist <per@hultqvist.nu>
Date: Sat, 19 Oct 2024 16:27:24 +0200
Subject: [PATCH] New example : core/storage_values

---
 examples/core/storage_values/main.go | 127 +++++++++++++++++++++++++++
 1 file changed, 127 insertions(+)
 create mode 100644 examples/core/storage_values/main.go

diff --git a/examples/core/storage_values/main.go b/examples/core/storage_values/main.go
new file mode 100644
index 0000000..8e4c658
--- /dev/null
+++ b/examples/core/storage_values/main.go
@@ -0,0 +1,127 @@
+/*******************************************************************************************
+*
+*   raylib [core] example - Storage save/load values
+*
+*   Example originally created with raylib 1.4, last time updated with raylib 4.2
+*
+*   Example licensed under an unmodified zlib/libpng license, which is an OSI-certified,
+*   BSD-like license that allows static linking with closed source software
+*
+*   Copyright (c) 2015-2024 Ramon Santamaria (@raysan5)
+*
+********************************************************************************************/
+package main
+
+import (
+	"encoding/binary"
+	"fmt"
+	"os"
+
+	rl "github.com/gen2brain/raylib-go/raylib"
+)
+
+const (
+	screenWidth     = 800
+	screenHeight    = 450
+	storageDataFile = "storage.data"
+	// NOTE: Storage positions must start with 0, directly related to file memory layout
+	storagePositionScore   = 0
+	storagePositionHiscore = 1
+)
+
+func main() {
+	rl.InitWindow(screenWidth, screenHeight, "raylib [core] example - storage save/load values")
+
+	var score int32
+	var hiscore int32
+	var framesCounter int32
+
+	rl.SetTargetFPS(60) // Set our game to run at 60 frames-per-second
+
+	// Main game loop
+	for !rl.WindowShouldClose() { // Detect window close button or ESC key
+		// Update
+		if rl.IsKeyPressed(rl.KeyR) {
+			score = rl.GetRandomValue(1000, 2000)
+			hiscore = rl.GetRandomValue(2000, 4000)
+		}
+
+		if rl.IsKeyPressed(rl.KeyEnter) {
+			_ = SaveStorageValue(storagePositionScore, score)
+			_ = SaveStorageValue(storagePositionHiscore, hiscore)
+		} else if rl.IsKeyPressed(rl.KeySpace) {
+			// NOTE: If requested position could not be found, value 0 is returned
+			score, _ = LoadStorageValue(storagePositionScore)
+			hiscore, _ = LoadStorageValue(storagePositionHiscore)
+		}
+
+		framesCounter++
+
+		// Draw
+		rl.BeginDrawing()
+		rl.ClearBackground(rl.RayWhite)
+
+		rl.DrawText(fmt.Sprintf("SCORE: %d", score), 280, 130, 40, rl.Maroon)
+		rl.DrawText(fmt.Sprintf("HI-SCORE: %d", hiscore), 210, 200, 50, rl.Black)
+
+		rl.DrawText(fmt.Sprintf("frames: %d", framesCounter), 10, 10, 20, rl.Lime)
+
+		rl.DrawText("Press R to generate random numbers", 220, 40, 20, rl.LightGray)
+		rl.DrawText("Press ENTER to SAVE values", 250, 310, 20, rl.LightGray)
+		rl.DrawText("Press SPACE to LOAD values", 252, 350, 20, rl.LightGray)
+
+		rl.EndDrawing()
+	}
+
+	// De-Initialization
+	rl.CloseWindow() // Close window and OpenGL context
+}
+
+// SaveStorageValue saves an integer value to storage file (to defined position)
+// NOTE: Storage positions is directly related to file memory layout (4 bytes each integer)
+func SaveStorageValue(position uint32, value int32) error {
+	// Load the file data
+	fileData, err := os.ReadFile(storageDataFile)
+	if err != nil && !os.IsNotExist(err) {
+		return fmt.Errorf("failed to load file: %v", err)
+	}
+
+	dataSize := len(fileData)
+	requiredSize := int((position + 1) * 4) // Each int32 is 4 bytes
+	newFileData := make([]byte, requiredSize)
+
+	// Copy existing file data to newFileData
+	if dataSize > 0 {
+		copy(newFileData, fileData)
+	}
+
+	// Update the value at the specified position
+	binary.LittleEndian.PutUint32(newFileData[position*4:], uint32(value))
+
+	// Save the updated data back to the file
+	err = os.WriteFile(storageDataFile, newFileData, 0644)
+	if err != nil {
+		return fmt.Errorf("failed to save file: %v", err)
+	}
+
+	return nil
+}
+
+// LoadStorageValue loads an integer value from storage file (from defined position)
+// NOTE: If requested position could not be found, value 0 is returned
+func LoadStorageValue(position uint32) (int32, error) {
+	// Load the file data
+	fileData, err := os.ReadFile(storageDataFile)
+	if err != nil {
+		return 0, fmt.Errorf("failed to load file: %v", err)
+	}
+
+	dataSize := len(fileData)
+	if dataSize < int((position+1)*4) {
+		return 0, fmt.Errorf("position out of bounds")
+	}
+
+	// Read the value at the specified position
+	value := int32(binary.LittleEndian.Uint32(fileData[position*4:]))
+	return value, nil
+}